Extended coherence time on the clock transition of optically trapped Rubidium

TL;DR

This paper demonstrates a significant extension of coherence time to 21 seconds in optically trapped Rubidium-87 using spin self-rephasing, enhancing the potential for compact, high-stability atomic clocks and quantum memories.

Contribution

The study shows the application of spin self-rephasing to extend coherence time in optically trapped atoms, confirming its general applicability for atomic clocks and quantum memories.

Findings

Coherence time extended to 21 seconds using spin self-rephasing.

Achieved stability of 2.4E-11 x tau^(-1/2), comparable to microwave fountain clocks.

Systematic analysis of frequency shifts and noise contributions.

Abstract

Optically trapped ensembles are of crucial importance for frequency measurements and quantum memories, but generally suffer from strong dephasing due to inhomogeneous density and light shifts. We demonstrate a drastic increase of the coherence time to 21 s on the magnetic field insensitive clock transition of Rb-87 by applying the recently discovered spin self-rephasing. This result confirms the general nature of this new mechanism and thus shows its applicability in atom clocks and quantum memories. A systematic investigation of all relevant frequency shifts and noise contributions yields a stability of 2.4E-11 x tau^(-1/2), where tau is the integration time in seconds. Based on a set of technical improvements, the presented frequency standard is predicted to rival the stability of microwave fountain clocks in a potentially much more compact setup.